The present invention relates to a stator blade assembly usable in an exhaust pump suitable as gas evacuation means of a process chamber or other sealed chambers of a semiconductor production device, a flat panel display production device, and a solar panel production device, and also relates to an exhaust pump provided with such a stator blade assembly. More particularly, the present invention is aimed at the improvement of evacuation performance by shortening an evacuation time of the exhaust pump.
A vacuum pump described, for example, in Japanese Patent Application Publication No. 2003-269365 is known as an exhaust pump of this kind. As shown in FIG. 13 of Japanese Patent Application Publication No. 2003-269365, the vacuum pump described in Japanese Patent Application Publication No. 2003-269365 has a structure in which a plurality of rotor blades (9) protruding from an outer circumferential surface of a rotatable rotor (2) and a plurality of stator blades (10) protruding toward the outer circumferential surface of the rotatable rotor (2) are arranged alternately in multiple stages along an axis of the rotor (2).
Referring to FIGS. 3 and 4 of Japanese Patent Application Publication No. 2003-269365, a plurality of stator blades (10) positioned in any one stage, from among the aforementioned stages, have a structure in which inner and outer blade bases are supported by frames (10-1, 10-2) for each stage.
However, in the vacuum pump described in Japanese Patent Application Publication No. 2003-269365 presented hereinabove by way of example, slits (102-2, 102-3) are formed by cutting in the vicinity of a blade base in order to incline the stator blade (10) at a predetermined angle, as shown in FIG. 1 of Japanese Patent Application Publication No. 2003-269365, and the stator blade (10) is bent. The resultant problem is that a gap unavoidably appears in the vicinity of the blade base of the stator blade (10) due to the slits (102-2, 102-3), which are necessary to perform such bending, and gas molecules flow in reverse (internal leak) through this gap, thereby increasing the time required to reach the desired degree of vacuum after the evacuation is started (referred to hereinbelow as “evacuation time”).
Referring to FIG. 4B of Japanese Patent Publication No. 4517724, in a vacuum pump described in Japanese Patent Publication No. 4517724, one stator blade (21(A)) and a stator blade (21(C)) transversely adjacent thereto are formed as a stator blade assembly of a double-layer stacked structure by supporting the respective blade bases with separate frames (23) (see FIG. 4A of Japanese Patent Publication No. 4517724) and superimposing those frames (23) in the vertical direction, this assembly representing a specific configuration of a plurality of stator blades (21) positioned in each stage that has been explained hereinabove.
However, in the stator blade assembly of a double-layer stacked structure such as described in Japanese Patent Publication No. 4517724, the frames (23) superimposed in the vertical direction can be opened in the vertical direction due to warping or bending. A problem caused by such opening of the frames (23) is that the height of the stator blades (23) becomes uneven and the decrease in evacuation efficiency caused by such unevenness increases the evacuation time.
Another problem associated with the stator blade assembly of a double-layer stacked structure such as described in Japanese Patent Publication No. 4517724 is that since the frames (23) are superimposed in the vertical direction, gas or fluid can be confined between the vertically superimposed frames (23), the gas or fluid, which has thus been confined, continuously and gradually flows out during the evacuation operation from the portion where the frames (23) are superimposed, thereby also extending the evacuation time.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.